Temperature dependence of large hyperfine coupling: SeO43- radical and evidence against a 310 K phase transition in KH2PO4

Anharmonic and Quantum Effects in KDP-Type Ferroelectrics: Modified Strong Dipole–Proton Coupling Model

“…The calculated difference between activation energies ∆E in DKDP and KDP (0.09 eV) is larger than experimental difference (0.03 eV) and decrease of the preexponential factor τ c0 to the value τ c0 = 6 × 10 -15 s in DKDP is not reproduced here. As in the case of original dipole, the mean square of local order parameter, c 2 , shows some temperature dependence [71], which indicates that the observed temperature dependence of hyperfine tensor of the SeO 4 3-radical in KDP and DKDP [53] could be partly caused by this effect and not solely by excitation of some extra lattice vibration mode.…”

“…To determine static properties of the SeO 3-4 radical in KDP and DKDP, the temperature dependence of the hyperfine interaction between unpaired electron and 77 Se (I = 1/2) nucleus was measured [53]. The hyperfine tensor component A || , where the direction || is along the c-axis, shows an isotope effect, because its value is higher in DKDP than in KDP.…”

Modified strong dipole-proton coupling model and local properties of EPR probe in KDP-type ferroelectrics

“…Regarding the static properties of the SeO43-probe, the temperature dependence of the hyperfine interaction between the unpaired electron and 77Se ([ = 1/2) nucleus was measured in KDP and DKDP [12]. The hyperfine tensor component A,, where the direction "parallel" is along the c-axis, exhil0its a larger value for DKDP than that for KDP and 3umi~s at Te for DKDP.…”

Coexistence of Order–Disorder and Displacive Behavior of KH2PO4 and Analogs from Electron Paramagnetic Resonance

“…Extensive EPR [14][15][16][17][18][19][20][21][22]30] and ENDOR [16,30,34,38] studies have also been carried out on the KDP family using the SeO 4 3probe. In short, the results obtained are fairly similar to those described above for the AsO 4 4center.…”

“…The present undertaking discusses the utilization of electron paramagnetic resonance (EPR) spectroscopy for investigating dielectric solids that are diamagnetic in their native state, but can be made slightly paramagnetic by lightly doping them with transition ions, such as Fe 3+ , as pioneered by Müller [2][3][4][5][6][7], or by using molecular probes such as the CrO 4 3-(Cr 5+ ) ion [1,[8][9][10][11][12][13], SeO 4 3radical [14][15][16][17][18][19][20][21][22] and the AsO 4 4center [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. While Müller's studies using Fe 3+ as a probe in SrTiO 3 and LaAlO 3 are considered as some of the classic examples of the power of EPR technique in probing microscopic mechanisms of phase transitions in the perovskites [2][3]…”